Relatively precise control of the geometry of a composite component can be achieved by using a resin transfer moulding (RTM) process. A dry reinforcement preform is laid up on a mould tool, a second mould tool is clamped over the first, and resin is injected into the cavity. The spacing between the mould tools (and hence the thickness of the component) can be controlled by mutual engagement between the mould tools around the edge of the component. Unfortunately such mould tools can be expensive to manufacture and handle, particularly where the component is a large component such as an aircraft wing or fuselage skin panel.
Lower cost methods are available which require only a single mould tool. However in these cases it is difficult to accurately control the geometry of the component.